docs: def easter(year=None):
      """
      1900 - 2099 limit
      :param year: int
      :return: Easter day
      """
      y = int(year) if year else _year
      n = y - 1900
      a = n % 19
      q = n // 4
      b = (7 * a + 1) // 19
      m = (11 * a + 4 - b) % 29
      w = (n + q + 31 - m) % 7
      d = 25 - m - w
      if d > 0:
          return datetime.date(y, 4, d)
      else:
          return datetime.date(y, 3, (31 + d))